8.1 - balancing equations
1, How can you determine what is a reactant and what is a product?
2. What is the law of conservation of matter?
1. Reactants are on the left side. Products are on the right side.
2. The law of conservation of matters states that in chemical reactions, atoms are neither created nor destroyed.
(The reactant and product sides must have the same number of each atom.)
how do you identify a double displacement reaction?
1. A single displacement reaction will have this formula:
element + compound --> element + compound
2. A double displacement reaction will have this formula:
Compound + compound ---> Compound + compound
what DO YOU HAVE TO DO WHEN PREDICTING THE PRODUCTS OF ANY EQUATION?
You have to:
1. Find the charges of elements
2. If one is negative, and one is positive, then bond them.
3. Make sure charges equal 0.
4. Balance equation afterwards.
how do you convert from mol to mol?
you convert from mol to mol using a conversion factor (the coeffecients from the balanced equation)
3H2 + N2 --> 2NH3
10.0 mol H2 x 2 mol NH3 / 3 mol H2 = 6.67 mol NH3
complete this chart for polyatomics INCLUDE THE NAME AND THEIR CHARGE
NH4
HCO3
CH3COO
NO2
NO3
OH
MnO4
CN
CO3
SO3
SO4
PO4
NH4 - ammonium -1
HCO3 - bicarbonate -1
CH3COO - acetate -1
NO2 - Nitrite -1
NO3 - Nitrate -1
OH - hydroxide -1
MnO4 - permangranate -1
CN - Cyanide -1
CO3 - carbonate -2
SO3 sulfite -2
SO4 sulfate -2
Phosphate PO4 -3
1. How do you balance a chemical equation? What does a coefficient look like? What does a subscript look like?
1. To balance a chemical equation, you add coefficients (big number) and multiply the coefficient to the subscripts (small number)
1. HOW DO YOU IDENTIFY A COMBUSTION REACTION?
2. What is an acid? What is base?
How do you identify a neutralization reaction?
1. you identify a combustion reaction by looking for CO2 + H2O AS PRODUCTS
hydrocarbon + O2 as reactants
2. What is an acid? Most acids start with H because they contain H+
ex. HCl, HNO3, H3PO4
What is base?
A base is something that contains a hydroxide (OH)
How can you identify a neutralization (acid-base) reactions?
When an acid + base react to form water (H2O)
ex. NaOH + HCl --> H2O + NaCl
how do you predict the products of a synthesis reaction?
How do you predict the products of a decomposition reaction?
1. in Synthesis reactions, combine both reactants to one compound (product) : A + B ---> AB
Find charges and make charges equal 0
2. To predict the products of a decomposition reaction, use AB ---> A + B
ONE REACTANT
break elements up into constituent elements ( individual atoms that make up a compound)
what to do if you're converting from grams to mol?
1. you convert from grams to mol, then from mol to mol, and then from mol to grams (or whatever is being asked for)
2. What are the conversion factors for molecules, mol, and liters?
Molecules- 6.022 x 10 ^ 23
Mol - 1 mol
liters - 22.7 L
What are the exceptions with charges?
Ag - silver's charge is always +1
Zn- zinc's charge is always +2
Cd- Cadmium's charge is +2
Fill in the blanks for tips on balancing equations
1. Balance all atoms but ______ and _______ first.
2. Leave any elements to balance _______
3. When stuck, multiply the __________ by ________ and try again.
1. Balance all atoms but __HYDROGEN____ and __OXYGEN___ first.
2. Leave any elements to balance __LAST_____
3. When stuck, multiply the ___LARGEST COMPOUND_______ by __2______ and try again.
How do you identify a precipitation reaction?
What do these symbols mean?
1. A precipitation reaction is when two aqueous solution are mixed and form a solid
2. (s) - solid (g)- gas (aq) - aqueous
(l) - liquid
1. How do you predict the products of combustion reaction?
2. How do you predict the products of single displacement reactions?
1. In combustion reactions, there will be
something + O2
products should be CO2+ H2O , then balance equation.
2. In single displacement reactions, it will be
AB + C --> AC + B
find charges (one negative charge and one positive charge so they will bond)
what is the theoretical yield?
what formula for percent yield?
1. Theoretical yield is the "supposed amount"/ how much you get when you solve
2. The formula for percent yield is
actual amount/ theoretical amount x 100
(USE SIG FIGS)
WORD PROBLEMS, BALANCING WORD PROBLEMS
1. How do you identify the formula of elements/compounds in word problems?
2. AFTER MAKING THE EQUATION FOR WORD PROBLEMS, WHAT DO YOU DO NEXT?
3. What is special about elements in GROUP 17? WHAT ARE THEY CALLED?
1. You identify the formula by finding the charge of both elements mentioned (the reactants) then you make the charges equal 0 and then you bond
ex. aluminum oxide
Al +3(2) = 6 O -2 (3) = -6 Al2O3
2. After making the equation for word problems, then you balance the equation.
3. Elements in group 17 are called halogens and they are diatomic (also ELEMENTS THAT END IN -GEN) EX. oxygen ---> O2
How do you identify redox reactions?
What type of reactions are always redox and why?
What is oxidation?
What is reduction?
1. A redox reaction is any reaction where an atom is unbonded on one side of the reaction and bonded on the other side.
2. Single displacement reactions are always redox because there is a free element that has no charge by itself, but when it replaces, it will have a charge in the compound
4. Oxidation is an element becoming more positive (loss of electrons)
Reduction is becoming more negative ( gain of electrons)
1. how do you predict the products of double displacement reaction?
1. In double displacement reactions, the formula should be:
AB + CD ---> AD + CB
What is the limiting reactant?
What is the excess reactant?
How do you find out how much was ACTUALLY FORMED?
1. The limiting reactant is the amount that forms the least of the product.
2. The excess reactant is the amount that forms the most product.
3. The amount produced from the limiting reactant is how much was actually formed.
1. How do you identify a synthesis reaction?
2. How do you identify a decomposition reaction?
1. In a synthesis reaction, TWO OR MORE REACTANTS FORM ONE PRODUCT.
2. In a decomposition reaction, ONE REACTANT PRODUCES TWO OR MORE PRODUCTS.
how can you remember oxidation when looking at an equation?
How can you remember reduction when looking at an equation?
What should you remember by elements by itself? How do you find the charge of elements?
1. You can remember oxidation when looking at an equation by looking to see if the charge INCREASES FROM ONE SIDE TO THE OTHER
2. you can remember reduction when looking at an equation by looking to see if the charge DECREASES from ONE SIDE TO THE OTHER.
3. An element by it self's charge is 0.
To find the charge, use the periodic table to reach nearest noble gas. Going left = positive charge
going right= negative charge
2. how do you predict the products of a neutralization reaction?
2. In neutralization reactions, one of the products must be water (H2O) and an acid + base as reactants
How do you find the excess/left over?
1. To find the excess/ left over, convert grams of the LIMITING REACTANT TO GRAMS OF THE EXCESS REACTANT
2. Subtract the excess from the excess reactant
and that is how much is left over!